In 1997, many East Asian currencies suddenly and dramatically devalued. What is the percentage change in value

Question:

In 1997, many East Asian currencies suddenly and dramatically devalued. What is the percentage change in value of a $50 million investment in Indonesia when the changes from $1 = 2,000 rupiah to $1 = 10,000 rupiah?

Exchange Rate
The value of one currency for the purpose of conversion to another. Exchange Rate means on any day, for purposes of determining the Dollar Equivalent of any currency other than Dollars, the rate at which such currency may be exchanged into Dollars...